Carbonyl bis-urethane production



United States Patent 3,505,392 CARBONYL BIS-URETHANE PRODUCTION Vincent Kerrigan and Kenneth William Pearson, Manchester, England, assignors to Imperial Chemical Indusn'ies Limited, London, England, a corporation of Great Britain No Drawing. Filed June 17, 1966, Ser. No. 558,264 Claims priority, application Great Britain, July 30, 1965, 32,706/ 65 Int. Cl. C07c 127/16 U.S. Cl. 260-479 3 Claims ABSTRACT OF THE DISCLOSURE A process for the manufacture of carbonyl bisurethanes which comprises reacting a N-unsubstituted carbamic ester with phosgene in the absence of acid-binding agents, and in a polar organic liquid inert to phosgene and containing at least one oxygen atom in the molecule as solvent.

This invention relates to a new chemical process and more particularly to a new and improved process for the manufacture of carbonyl bisurethanes.

It is well-known that carbonyl bisurethanes can be manufactured in general, by the interaction of a carbamic ester and phosgene. Since both the carbamic ester and the carbonyl bisurethane derived therefrom are, with rare exceptions, solids at ordinary temperatures it is convenient and eflicient to carry out the reaction in a solvent and to recover the final product bythe usual steps of evaporation and concentration. Hitherto, however, it has been considered necessary, when using a solvent, to carry out the reaction in the presence of acid-binding agents, or more especially pyridine, which has introduced expense either directly in the cost of material or indirectly in the form of additional complications in workingup procedures and recovery of solvents. It has now been found however that phosgenation of carbamic esters can be carried out expediently and in the absence of acidbinding agents by using as solvents polar organic liquids containing at least one oxygen atom in the molecule.

According to the invention there is provided a process for manufacture of carbonyl bisurethanes which comprises reacting a N-unsubstituted carbamic ester with phosgene in the absence of acid-binding agents, and in a polar organic liquid, containing at least one oxygen atom in the molecule, as solvent. It is preferred to use as solvent a carboxylic acid ester, an ether and/or a N,N- disubstituted carbamic ester which is inert to phosgene.

As examples of carbamic esters which may be used, there may be mentioned alkyl, aralkyl, cycloalkyl and aryl car-bamates, such as n-propyl carbamate, isopropyl carbamate, ethyl carbamate, n-butyl carbamate, isobutyl carbamate, sec-butyl carbamate, amyl carbamates, hexyl carbamate, cyclohexyl carbamate, methyl cyclohexyl carbamate, phenyl carbamate, and 0, m or p-methyl phenyl carbamate.

The solvents used in the new process should be inert to phosgene and for this purpose should be free from groups, such as hydroxyl, amino and monosubstituted amino, which are themselves reactive with phogene. As examples of solvents which can be used, there may be mentioned:

CARBOXYLIC ACID ESTERS Suitable solvents include alkyl, cycloalkyl, aralkyl, alkenyl and substituted alkyl esters of aliphatic monocarboxylic acids such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secbutyl, amyl, isoamyl, hexyl, heptyl, cyclopropyl, cyclohexyl, benzyl, phenylethyl, vinyl, allyl, isopropenyl, 2 methoxyethyl, 2 ethoxyethyl, 2 butoxyethyl, 2 (B methoxyethoxy)ethyl, 2-

3,505,392 Patented Apr. 7, 1970 "ice (,8 ethoxyethoxy)ethyl and 2 (B butoxyethoxy)ethyl esters of acetic, propionic, butyric, isobutyric, valeric, hexoic, pivalic, octoic methoxyacetic, ethoxyacetic and phenylacetic acids; lower alkyl, alkenyl and cycloalkyl esters of aromatic monocarboxylic acids such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, allyl and cyclohexyl esters of benzoic, 0-, mor p-toluic and omethoxybenzoic acids, lower alkyl esters of aliphatic and aromatic dicarboxylic acids such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl and amyl esters of succinic, glutaric, adipic, pimelic, suberic, azelaic, maleic and phthalic acids; alkyl esters of carbonic acid such as dimethyl, diethyl, diisopropyl, dipropyl and dibutyl carbonates; and monocarboxylic esters of polyhydroxy compounds such as the acetates, propionates, butyrates, hexoates, cyclohexoates, cyclopentoates, benzoates, and o, m or p-methylbenzoates of ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 2:2- diethyl propan-1:3-diol, 2-methyl-2-propylpropan 1:3- diol, 2-ethyl-2-butylpropan-l:3-diol, neopentyl glycol, 1 :S-pentanediol, 2-methyl-pentan-l :3-diol, 2:2-dimethylbutan 1:3 diol, 2:224 trimethylpentan 1:3 diol, 2 ethylhexan 1:3 diol, hexylene glycol and 122:6- hexantriol.

ETHERS Suitable solvents include bisalkyl, cycloalkyl, aralkyl, alkenyl and aryl ethers such as diethyl, diphenyl, dipropyl, diisopropyl, dibutyl, dihexyl, dicyclohexyl, ethyl-npropyl, methylisopropyl, ethyl-n-butyl, methylphenyl, ethylphenyl ethers; 1:1:3-triethoxyhexane, ethylene diethyl ether, ethylene di-n-butylether; diethyl, dimethyl, di-nbutyl ethers of diethylene glycol and triethylene glycol, etc., and cyclic ethers such as tetrahydrofuran, 1:4-dioxan, 1 :3-dioxan, 2-methyl-2-ethyl-1 3-dioxan.

CARBAMIC ESTERS Suitable solvents are, for example, methyl-dimethyl carbamate, n-propyldirnethyl carbamate, isopropyl dimethyl carbamate, n-butyldimethyl carbamate, isobutyl dimethyl carbamate, allyldimethyl canbamate, 2-ethylhexyldimethyl carbamate, isooctyl dimethyl carbamate, decyldimethyl carbamate, dodecyldimethyl carbamate, tridecyldimethyl carbamate, stearyldimethyl carbamate, ethyldiethyl carbamate, ethyldicyclohexyl carbamate, ethyl- N-methyl-N-phenyl carbamate, N-carbethoxymorpholine, N-carbethoxypiperidine, ethylene-bis-(NzN-dimethyl carbamate), propylene-bis-(N:N-dimethyl carbamate), hexamethylene-bis-(NzN-dimethyl carbamate), 3-oxa-penta methylene-bis-(N:N-dimethyl carbamate), phenyldimethylcarbamate, p-chlorophenyldimethyl carbamate, 0, mor p-methylphenyldimethyl carbamates, benzyldimethyl carbamate, cyclohexyl dimethyl carbamate, NzN-bis-carbethoxypiperazine, N-carbethoxytetrahydroquinoline.

If desired, these preferred solvents can be used in admixture with other non-oxygenated phosgenation solvents, such as benzene, toluene, xylene, chlorobenzene and dichlorobenzene.

The new process can conveniently be carried out by heating a mixture of the reactants under reflux until reaction is complete, as indicated by the rate of evolution of hydrogen chloride. Thereafter the final product can be obtained by evaporating the solvent and purified, if desired, for example, by recrystallization of the residue, lixiviation with water or other means. The new process offers advantages over the previously proposed processes in being fundamentally cheaper and offering simpler isolation techniques.

The invention is illustrated but not limited by the following cxamples in which parts are by weight:

Example 1 To a stirred suspension of parts of isopropylcarbamate in 270 parts of butylacetate, maintained at 0 C 3 by external cooling there are added 90 parts of phosgene. The slurry is then heated slowly to 60 C. during about 1% hours and the temperature is maintained at 60 for four hours. During this period the phosgene is allowed to reflux. The solution is then degassed by passing dry nitro- 4 80100 C. petroleum ether. The yield of carbonylbis- (sec-butyl urethane) is 85% of theory.

Example 5 To a stirred solution of 114 parts of isoamyl carbamate th h th t t 780 C in 350 parts of butyl acetate, maintained at 0 C. by exg g h t h th fil ternal cooling there are added 110 parts of phosgene. The g to W en solution is then stirred for 2 hours at 10 C., heated to an t F fg arefils 1 8 preisuref 60 C. during 1 hour and maintained at this temperature to 56 3 g a a 3 for a further hours. During this period phosgene is ga i O 2 7 i e 10 passed into the reaction mixture at the rate of 15 parts 0 Cal (my musopmpy we ans) 0 O per hour. The solution is then degassed at 65 C. by pas- Example 2 sage of dry air through the mixture. The solution is cooled to 50 C. and the solvent is dis- To a stlrred suspension of 51.5 parts of isopropyl carbamate in 90 parts of ethyl-N,N-dimethylcarbamate, 15 gg zi fig i g g gg g 231 rj i 2 maintained at 0 C. by external cooling, there are added f f e yle 37 parts of phosgene. The slurry is then heated slowly to Car my 15 lsoamy ure am is 0 o eory' 50 C. during about 1% hours. During this period the Examp 6 phosgene is allowed to reflux. The solution is then de- To a stirred suspension of 150 parts of methyl carbagassed at 75 C. by passage of dry nitrogen through the mate in 250 parts of dioxan, maintained at 0 C. by we mixture. ternal cooling there are added 110 parts of phosgene. The The solution is cooled to 20 C., screened from a trace mixture is then heated slowly to 40 C. and this temof insoluble material and the filtrates are distilled under perature is maintained for a further 10 hours. During this reduced pressure to dryness. The solid residue is recrystalperiod phosgene is introduced into the reaction mixture lised from 70 parts of 80l00 C. petroleum ether. The at the rate of 20 parts per hour. The solution is then deyield of carbonylbis(isopropylurethane) is 69% of theory. gassed at 40 C. by passage of dry air through the mixture. Exam 1g 3 Carbon is added to the warm solution and the mixture p is then filtered and the filtrates are distilled under reduced To a stirred suspension of 51.5 parts of n-propyl carpressure to dryness. The solid residue is recrystallised bamate in 125 parts of dioxan, maintained at 0 C. by 6X- from hot acetone. The yield of carbonyl bis(methylur ternal cooling are added 30 parts of phosgene. The susthane) is 55% of theory. pension is then heated to 60 C. during about 1% hours Example 7 and this temperature is maintained for a further 3 hours. If Exam 1e 6 the 150 a ts of In th 1 b t r During this period the phosgene is allowed to reflux. The re lalced b 5 a ts of i 1 g g 3 g g solution is then degassed at 70 c. for 3 hours and 90 fi of g 35 i 6 e argon I C. for 1 hour by passage of dry nitrogen through the p g y p p g c mixture brs(Phenylurethane) is obtained. The yield is approxi- The solution is distilled under reduced pressure to drymately 50% of theory Exam 1e 8 mess. The solid residue is recrystallised from 70 parts of P 80-100 C. petroleum ether. The yield of carbonylbis(n- A suspension of 175 parts of isobutyl carbamate in 400 propylurethane) is 85% of theory. parts of methyl isobutyrate is cooled to 5 C. by external E am 1 4 cooling and kept at this temperature whilst 75 parts of X p e phosgene are added. The suspension is then heated to 70 A suspension of 58.5 parts of sec-butyl carbamate in C. during 1% hours and this temperature is maintained 150 parts of diethyl carbonate is cooled to 0 C. by exfor a further 9 hours. During this period phosgene is ternal cooling and kept at this temperature whilst 35 parts passed into the reaction mixture at the rate of 20 parts per of phosgene are added. The suspension is then heated to hour. The solution is then degassed by the passage of dry 60 C. during about 1% hours and this temperature is air through the mixture. maintained for a further 4 hours. During this period the The solution is distilled under reduced pressure to dryphosgene is allowed to reflux. The solution is then deness and the solid residue is recrystallised from 300 parts gassed at 70 C. by passage of dry nitrogen through the of 80100 C. petroleum ether. The yield of carbonyl bis mixture. (isobutylurethane) is 80% of theory.

The solution is distilled under reduced pressure to dry- The following table lists further examples of the inness. The solid residue is recrystallised from 70 parts of vention.

Yield of carbonyl Time Temp. bisurethane, Ex. No. Oarbamate Solvent (hrs) 0.) percent 9 Ethyl n-Propyl- 10 50 carbonate. l0 Isopropyl Methylbenzoate 1O 70 70 11 Sec. but-yl Cyclohexyl 1O 70 82 acetate. 12 50/50 mixture Ethyleneglycol 0% 65 isopropyl/ diaeetate. sec. butyl. 13 Hexyl Ethyl snccinate 10 68 14 Cyclohexyl Ethyl-N-rnethyl- 9% 70 N-phenylcarbamate. 15 Isopropyl Ethyl-N:N- 5 65 65 dirnethylthiolearbamate. 16 "do Butyl acetate 10 70 9.2. 5 17 50/50 mixture d0 10 70 95 isopropyl/sec. butyl carbamates. 18 Isopropyl Phenetole 10 70 40 earbamate. 10 do Sulpholane 10 70 36 20 "do 50/50buty1 10 70 acetate/toluene.

What we claim is:

1. A process for the manufacture of carbonyl bisurethanes which comprises reacting by contacting at a temperature up to reflux a N-unsubstituted carbamic ester with phosgene in the absence of acid-binding agents, and in an organic liquid comprising at least 50% by weight of a polar organic liquid inert to phosgene, containing at least one oxygen atom in the molecule and selected from the group consisting of carboxylic acid esters, ethers, N,N- disubstituted carbamic esters and sulpholane as solvent.

2. A process as claimed in claim 1 wherein the organic liquid contains non-oxygenated solvents which are inert to phosgene in an amount up to 50% by weight.

3. A process as claimed in claim 2 wherein said other sisting of benzene, toluene, xylene, chlorobenzene and dichlorobenzene.

References Cited UNITED STATES PATENTS OTHER REFERENCES Beilstein: Mainwork band 3, pp. 63 citing Schmidt.

JAMES A. PATTEN, Primary Examiner US. Cl. X.R.

nonoxygenated solvents are selected from the group con- 15 260482 

